Lamp base



FIG. 1 is a top plan view of a lamp base showing my new design;

FIG. 2 is a front elevational view thereof, the sides and rear being identical;

FIG. 3 is a bottom plan view thereof; and

FIG. 4 is a fragmentary cross-sectional view taken along line 4--4 of FIG. 2. 

The ornamental design for a lamp base, as shown and described. 